Abstract: In the process for treating slag from refuse incineration plants, the crude slag, after passing through the firing grate, is separated into at least two fractions directly and without previous quenching in a water bath. These two fractions are further processed separately, the coarse fraction being fed to a wet deslagger. For optimum separation of the two fractions, the first fraction, having a particle size preferably up to 32 mm, is separated off in a first screening stage and the screen oversize of the first screening stage is fed to the wet deslagging. The screen undersize and if appropriate the material passing through the firing grate are fed to a second screening stage to separate off the fine fraction 0 . . . 2 mm. The screen oversize of the second screening stage, if appropriate after removing metallic and inert materials, is mechanically comminuted. In an optional third screening stage (8), the fine fraction 0 . . .